exponential curve S0S

Need help- greatly appreciate it!
Find an equation of an exponential curve that contains the points (3,85) and (7,13) . Show work and do not use the regression capabilities of your calculator. (The last part led to my demise)

Need help- greatly appreciate it!
Find an equation of an exponential curve that contains the points (3,85) and (7,13) . Show work and do not use the regression capabilities of your calculator. (The last part led to my demise)